Photolithography is a process used in semiconductor device fabrication to transfer a pattern from a mask to the surface of a wafer or substrate. One type of mask is an extreme ultraviolet mask (EUV) for use with EUV lithography. Mask substrates, mask blanks, and finished patterned masks are subject to stringent defect specifications. These defect specifications are outlined in the Semiconductor Equipment and Materials International (SEMI) standards document SEMI P37-1102 and SEMI P38-1103, which call for 0.003 defects/cm2 for the 45 nm node by the year 2009. Therefore, all processing steps, from the substrate level to a finished mask, have to generate as few defects as possible.
For tracking masks in an automated manufacturing environment, masks have to carry a permanent identification label that allows tracing a specific mask throughout its useful lifetime. Typically, these labels are applied to the surface of the mask substrate and destroy parts of that substrate surface. By destroying parts of the substrate surface, particle defects are generated.